net: xdp: report flags program was installed with on query

Some drivers enforce that flags on program replacement and
removal must match the flags passed on install.  This leaves
the possibility open to enable simultaneous loading
of XDP programs both to HW and DRV.

Allow such drivers to report the flags back to the stack.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -3392,6 +3392,7 @@ static int nfp_net_xdp(struct net_device *netdev, struct netdev_bpf *xdp)
 		if (nn->dp.bpf_offload_xdp)
 			xdp->prog_attached = XDP_ATTACHED_HW;
 		xdp->prog_id = nn->xdp_prog ? nn->xdp_prog->aux->id : 0;
+		xdp->flags = nn->xdp_prog ? nn->xdp_flags : 0;
 		return 0;
 	case BPF_OFFLOAD_VERIFIER_PREP:
 		return nfp_app_bpf_verifier_prep(nn->app, nn, xdp);

include/linux/netdevice.h

@@ -820,6 +820,8 @@ struct netdev_bpf {
 		struct {
 			u8 prog_attached;
 			u32 prog_id;
+			/* flags with which program was installed */
+			u32 prog_flags;
 		};
 		/* BPF_OFFLOAD_VERIFIER_PREP */
 		struct {